The present invention relates to a method for controlling an electric machine, having an encoder wheel which has a multiplicity of teeth and at least one reference marking. The present invention furthermore relates to a corresponding drive system and a corresponding vehicle.
Electric machines are used today in a multiplicity of applications. Electric machines are, e.g., particularly used in the automotive industry in order, in combination with an internal combustion engine or as a sole drive motor, to reduce the fuel consumption of a vehicle.
If the vehicle is driven by a combination of an internal combustion engine and an electric motor, it is referred to as a so-called hybrid vehicle. Depending on whether the internal combustion engine is arranged in series or in parallel with the electric motor, the vehicle is referred to as a series hybrid vehicle or as a parallel hybrid vehicle. Electric vehicles, on the other hand, have only an electric motor as the drive motor.
Due to the effort of the automobile industry to further reduce the fuel consumption of vehicles, such vehicles having electric drives will increasingly be used in the future. In the case of electric vehicles, the electric motor can, e.g., have a power output of 50 kW or more. In the case of hybrid vehicles, electric motors having a power output of approximately 15 kW-35 kW are typically used.
Power electronics, which control the torque and power output of the electric motors, are provided to actuate the electric motors. In so doing, this closed-loop control is based on at least one rotational speed signal which is detected in the electric motor.
The control quality depends greatly on the accuracy of the rotational speed detection. Hence, complex sensor systems, e.g. Vogt sensors or resolvers, are used, particularly in parallel hybrid vehicles and electric vehicles, to detect the rotational speed.